In conventional air conditioners, for example, in air conditioners for work vehicles, there is a structure in which a compressor of a refrigeration cycle is operated by an engine to form an air conditioner. Further, in a case where a room space of a work vehicle (for example, a space in a cabin) is large, or in a case where a thermal load varies greatly, there is a case where a plurality of compressors are used for a single refrigeration cycle and drive force transmission systems are provided for respective compressors. Furthermore, there is an air conditioner wherein, in a refrigeration cycle having two compressors, one is a fixed displacement-type compressor and the other is a variable displacement-type compressor (for example, Patent document 1).
In a case where two compressors are used, however, there is a problem that there is no means for properly determining a required cooling ability, or even if there is, if a proper determination is not carried out, the required cooling ability cannot be achieved, and further, a comfortable feeling of passengers cannot be obtained. Further, if the determination of excessive cooling ability is carried out properly, the loss of consumption power and the like may become great.
Patent document 1: JP-A-2003-19908